Methods and filling systems for filling containers and in particular for the pressurized filling of containers (filling of containers under stressing or filling pressure) with a liquid filling good, for example with a carbonated filling good or drink, are known in different embodiments, including in the form of rotary filling machines in particular. Here, at least during one phase of a filling process, in particular during the actual filling phase in which the filling of the container pre-stressed with the stressing pressure or filling pressure takes place, and/or during a stress phase and/or pre-stress phase preceding the filling phase, the respective container is pressed by a press-on force with a mouth edge surrounding its container opening tightly or in sealing position up against the filling element in the region of a dispensing opening located there for the liquid filling good.
It is also known in particular (EP 1 520 833 B1) that the press-on force can be produced by a pneumatic device, e.g. in the form of a pneumatic piston/cylinder arrangement, which is part of a lifting device for a container carrier carrying or holding the respective container during the filling process and pressing it against the filling element and which is subjected to the pressure (clamping or filling pressure) of a gaseous and/or vaporous process medium that is used during the filling process and being in the form of an inert gas used as a purging and/or stressing and/or pre-stressing gas. The filling system and/or the corresponding filling machine exhibit a plurality of filling elements each having a container carrier and associated lifting device.
One basic advantage of such a filling system lies in a simplified control of the lifting devices for the container carriers and also in particular in a reduction of the number of, and/or the load on, control elements on the filling element side, for example cam rollers that, in interaction with at least one static control cam, ensure the condition of the container carriers when lowered from the filling element at the container entry as well as at the container exit of the filling machine for transferring the empty containers to the filling elements or to the container carriers located there, and for removing the filled containers from the container carriers.
A disadvantage of such filling systems, however, is that the pressure of the purging and/or stressing and/or pre-stressing gas is predetermined by process parameters, in particular by parameters specific to the filling good, such as its nature, its CO2 content, and its temperature, and also by machine-related parameters, such as the throughput of the filling machine (filled containers per unit of time etc.). This pressure cannot easily be altered or can at best only be altered within certain limits.
If containers with different mouth diameters, for example bottles with mouth diameters of 28, 30 or 38 mm, are now to be filled on one and the same filling machine, then the pneumatic device that produces the press-on force must be designed to supply the clamping or press-on force that is sufficient for the containers with the biggest mouth diameter while taking into account the filling or stressing pressure. This also means, however, that this press-on force far exceeds the level required for containers with a smaller mouth diameter. This results in excessive press-on force exerting an unnecessarily high mechanical load on containers with a smaller mouth diameter. This can destroy or at least damage the containers, especially thin-walled containers and/or containers made from plastic.